|
Te reason it will not add anything is because it doesn't add random signal. Your images pre calibration are packed full of random and non random noise. Calibration frames remove the non random stuff eg. bias/dark current. What is left is the random noise.
The idea behind stacking is to get the average signal of what you want and the random noise is decreased by sqrt(n) with n being the number of subs.
What double stacking doesn't do is add any more random noise as it just repeats the random already there.
|